I've been to Washington, DC a few times. The last time, I was in the area, I visited the space and aircraft museum. It was filled with helicopters, planes, and so many other things it would take more than one day to really explore.
I know that Washington DC was envisioned by a Frenchman who wanted the city where everyone was equal. The architect used the natural rises to build the important building above so they shown.
The architect was never paid for his work and his vision did not become a reality till the early 1900's although not everything was done. While researching the history of Washington DC, I discovered that the Mathematical Association of America produced a guide explaining the math found on the National Mall. The National Mall is a National Park running through downtown DC.
The short 2 page field guide highlights the geometry seen along the length of the National Mall. For instance, it mentions the geometry of water spraying out of water fountains. It states the more spectacular patterns are due to the angle of the water coming out. It looks at a dozen different mathematical applications found along the mall.
If you look carefully, you'll find infinity, a Mobius sculpture, a truncated trapizoid, a pyramid, a fractal and so many other applications. Each description is short and to the point but the site also provides additional information on each highlighted feature. For instance, if you follow the link on the geometry of water fountains, you'll find a nice discussion on the mathematics and physics of creating a spectacular display.
The explanation is from the Mathematical Tourist who used material from a paper addressing this particular math topic. What factors control the look of a water fountain? Its really interesting and even goes so far as to discuss which angles provide the best results.
Just think! If you live in the area, you could take a field trip down to the National Mall and check out everything in the folder. If not, there is always Google Street view or Google Earth so students can check out all of the items in the Field Guide. Let me know what you think!